Apparatus for removing photoresist film

ABSTRACT

A photoresist film removing apparatus includes a reacting chamber, an ozonizer producing a gas supplied to the reacting chamber, and an exhaust system that exhausts the gas from the reacting chamber. A source of a photoresist film-remover is located opposite a stage carrying a substrate covered with photoresist. Photoresist film-remover and the gas are supplied to the substrate through apertures. An electric field may be generated between the source of the photoresist film-remover and the substrate. Alternatively, a centrally located feed tube supplies only one of the gas and the photoresist film-remover through a single aperture and a reservoir discharges the other through apertures. The reservoir surrounds and is sealed to the feed tube. The apparatus may include a container holding a liquid photoresist film-remover and a mixture of the gas and remover is supplied from outside the reacting chamber to the substrate.

This application is a division of U.S. patent application Ser. No.09/614,252 filed Jul. 12, 2000, now U.S. Pat. No. 6,517,998, which is acontinuation application of PCT international application No.PCT/JP99/06324 which has an international filing date of Nov. 12, 1999and which designated the United States, the entire contents of which areincorporated by reference.

FIELD OF THE INVENTION

The present invention relates to a method of removing a film containingan organic composition, particularly to a method of removing aphotoresist film containing an organic polymer composition used in aphotolithographic process for producing a semiconductor device and thelike, and to an apparatus used in the method.

DESCRIPTION OF THE RELATED ART

A photoresist material is generally used in a photolithographic processfor forming a fine pattern and/or in a subsequent etching step forforming an electrode pattern in course of manufacturing a semiconductordevice, such as an integrated circuit, a transistor, a liquid crystaldevice, a diode and the like.

For example, when a silicon oxide layer is formed in a desired patternon a semiconductor substrate such as a silicon substrate (referred to asa silicon wafer), a silicon oxide layer is first deposited on thesurface of the substrate and cleaned before a photoresist materialsuited for forming the desired pattern is applied to the silicon oxidelayer to form a photoresist film. Then, a photo mask having a patterncorresponding to the desired pattern is placed on the photoresist film,exposed to light and then developed. Thereby, a photoresist film havingthe desired pattern, referred to a photoresist pattern, is obtained. Inthe subsequent etching step, the silicon oxide layer is removedaccording to the resulting photoresist pattern. Finally, after theremoval of the remaining photoresist film and the cleaning of thesurface of the substrate, the silicon oxide layer is left on thesubstrate in the desired pattern.

In the etching step, an art-known method of removing a part of thephotoresist film unnecessary for the formation of the desired patternincludes, for example, [1] a method using an oxygen gas plasma and [2] amethod using various oxidizing agents.

In the method using an oxygen gas plasma [1], oxygen is introduced inthe photoresist film under vacuum and a high voltage to generate anoxygen gas plasma. Then, the photoresist film is decomposed and removedby reacting with the oxygen gas plasma. However, there had been someproblems in this method [1], including the requirement of an expensiveapparatus for generating the oxygen gas plasma, a potential of damagingthe substrate containing an electrical element due to the presence ofcharge carriers in the plasma, and the like.

Alternatively, as an example of the method [2] using various oxidizingagents to decompose and remove the photoresist film, for example, amethod using hot concentrated sulfuric acid or a mixture of hotconcentrated sulfuric acid and hydrogen peroxide as the oxidizing agentis known.

When using hot concentrated sulfuric acid, however, there is adisadvantage, such as an extremely high risk in heating strong sulfuricacid up to 150° C.

On the other hand, when using the mixture of hot concentrated sulfuricacid and hydrogen peroxide, a substance having an oxidizing anddecomposing action is released according to the following scheme. In thescheme, on adding hydrogen peroxide to hot concentrated sulfuric acidheated to about 140° C., peroxosulfuric acid (H₂SO₅; generally referredto as Caro's acid) and an oxygen atom (O) are generated as follows:H₂SO₄+H₂O₂

H₂SO₅+H₂O  (1)H₂O₂→O+H₂O  (2)

The organic photoresist film may be oxidized by the strong acidity ofboth peroxosulfuric acid and the oxygen atom to be converted to aninorganic substance. The inorganic substance is decomposed by reactingwith hot concentrated sulfuric acid and then removed from the surface ofthe substrate.

However, as shown in the above schemes (1) and (2), this method [2] hasa problem that, since a sulfuric medium is diluted with water producedupon every addition of hydrogen peroxide to hot concentrated sulfuricacid, the concentration of hot concentrated sulfuric acid, after mixing,is decreased with time. The method [2] also has disadvantages, includingthe extremely high risk as described for the method [1], i.e., the useof strong sulfuric acid at an elevated temperature, and the heatgenerated when mixing hot concentrated sulfuric acid with hydrogenperoxide, and the necessity of an expensive exhaust system generatingstrong ventilation in order to operate the method in a clean room, andthe like.

As another oxidizing agent used to decompose the photoresist film otherthan hot concentrated sulfuric acid, there has been developed awater-immiscible solution for exclusively removing a photoresist film,such as, for example, a solution #106 consisting of 30% by volume ofdimethylsulfoxide and 70% by volume of monoethanolamine. However, suchoxidizing agent has problems, including its lower oxidation power thanhot concentrated sulfuric acid and a mixture of hot concentratedsulfuric acid and hydrogen peroxide, and the difficulty of treating thefoul solution which is immiscible with water.

In order to overcome the problems of the methods [1] and [2], a methodof removing a photoresist film using a mixture of ozone with hotsulfuric acid as the oxidizing agent has been proposed (Japanese PatentKokai Publication No. Sho 57-180132). This publication disclosesdecomposing and removing the organic substance (i.e., the photoresistfilm) or the inorganic substance deposited on the substrate or theinsulating layer by bubbling an ozonized gas in hot sulfuric acid. Italso describes a washing apparatus used in the method (cross sectionalview of the apparatus is illustrated in FIG. 8).

The washing apparatus shown in FIG. 8 includes a quartz container 6″filled with hot concentrated sulfuric acid 5′ heated at approximately110° C., which is laid on a heater 11, and a quartz tube 120 havingplural outlets 3′. A raw gas (generally, oxygen) supplied through agas-introducing tube 111 provided outside the quartz container 6″ isconverted to an ozonized gas in an ozone generator 1. The ozonized gasis then injected through the quartz tube 120 into hot concentratedsulfuric acid 5′ in the quartz container 6 to react with sulfuric acid,and thereby, peroxosulfuric acid and an oxygen atom are produced.Oxidizing the photoresist film with the strong acidity of bothperoxosulfuric acid and oxygen causes the removal of the photoresistfilm from the surface of the substrate 8 (held with a substrate cassette9) immersed in hot concentrated sulfuric acid.

In the method described in the above publication, the concentration ofthe sulfuric acid does not change since water is not generated duringthe decomposition of the photoresist film, and, therefore, the frequencyof changing the sulfuric acid may be decreased. The method, however, hada problem that the cost for raw materials is too high because a largeamount of the sulfuric acid is needed to operate. Additionally, themethod and apparatus disclosed in the above publication also have a highrisk on working because of the use of strong sulfuric acid at anincreased temperature in the same way as the conventional method, andalso needs extremely strong ventilation since the oxidizing agent isvolatilized by bubbling the ozonized gas.

Accordingly, an object of the present invention is to provide a methodof removing a photoresist film at an increased rate, which decreasesboth usage of the raw materials and the cost for any exhaust system andis also environment-friendly, and to further provide an apparatus usedin the method, in order to overcome the above problems with theart-known method of removing the photoresist film and with theconventional apparatus used therefor.

Definition of Technical Terms

As used herein, an “ozonized gas” means a gas mixture containing oxygenand a given amount of ozone. Hereinafter, a “sealed system” isthermodynamically classified into an open system, but it means one inwhich any of a gas and a solution are introduced therein and a gas or avapour generated in removing a photoresist film according to the presentinvention, and the like, are not released or spattered to outside of thesystem.

SUMMARY OF THE INVENTION

According to the first aspect of the present invention there is provideda method of removing a photoresist film by in a sealed system, evenlyand continuously or intermittently supplying a photoresistfilm-removable mixture containing an ozonized gas and a photoresistfilm-remover to a photoresist film formed on a surface of a substratethrough a photoresist film-remover supplier arranged as opposed to thephotoresist film. The ozonized gas used in the present inventioncontains in an amount of at least 5 mole %, preferably 5 to 100 mole %of ozone based on the total amount of the ozonized gas.

In the method of the present invention, a distance between a surface ofthe photoresist film on the substrate and the photoresist film-removersupplier may be within a range of 1 to 5 mm. By adjusting the distanceto the above range, a rate of removing the photoresist film in themethod according to the present invention may be further increased.

In the method of the present invention, the ozonized gas and thephotoresist film-remover may be supplied separately or in a mixed form.The ozonized gas may be supplied under a high pressure of a rangebetween 1 atm (101, 325 Pa) and 5 atms (506, 625 Pa).

A suitable photoresist film-remover used in the present invention may beselected from organic solvents having a lower reactivity with ozone,including saturated alcohols, ketons and carboxylic acids.

In the method of the present invention, both a temperature of thephotoresist film-remover and a temperature at a region apart at least 5mm from the surface of the substrate are preferably set at a lowertemperature than the surface of the substrate.

In the present invention, most preferably, the ozonized gas may becontinuously supplied, and the photoresist film-remover may beintermittently supplied.

Further, the method of the present invention may comprise a means ofgenerating an electric field between the photoresist film-removersupplier and the surface of the substrate. By the means, the photoresistfilm-remover may be converted to a microparticle.

The second aspect of the present invention relates to an apparatuscomprising a reacting chamber equipped with an ozonizer and an exhaustsystem, a stage for fixing the substrate having the photoresist film onthe surface thereof, and a photoresist film-remover supplier arranged asopposed to the stage, wherein the stage and the photoresist film-removersupplier are distributed in the reacting chamber. An ozonized gas and aphotoresist film-remover which are used as the photoresistfilm-removable mixture may be continuously or intermittently supplied tothe surface of the substrate through the same or different aperturesformed in the photoresist film-remover supplier.

In the apparatus of the present invention, the reacting chamber may bemade of stainless steel or Teflon®-coated stainless steel, Teflon®resin, ceramics or Teflon®-coated ceramics, or a mixture thereof.

The ozonized gas used in the apparatus contains at least 5 mole %,preferably 5 to 100 mole % of ozone based on the total amount of theozonized gas.

The ozonized gas and the photoresist film-remover may be preliminarilymixed to supply as the photoresist film-removable mixture. In this case,the ozonized gas and the photoresist film-remover are preferablypreliminarily mixed to send the mixture thereof to the photoresistfilm-remover supplier and then supplied through the apertures.

In the apparatus of the present invention, a distance between a surfaceof the photoresist film on the substrate and the photoresistfilm-remover supplier may be within a range of 1 to 5 mm. The apparatusmay also comprise a means of heating the stage and/or a means of coolingthe photoresist film-remover. By using them, both a temperature of thephotoresist film-remover and a temperature at a region apart at least 5mm from the surface of the substrate may be set at a temperature lowerthan the surface of the substrate.

The apparatus may further comprise a means of heating the stage and/or ameans of cooling the photoresist film-remover.

In the present invention, the ozonized gas may be supplied to theapparatus under a high pressure of a range between 1 atm (101, 325 Pa)and 5 atms (506, 625 Pa).

A suitable photoresist film-remover used in the apparatus of the presentinvention may be selected from organic solvents having a lowerreactivity with ozone, including saturated alcohols, ketons andcarboxylic acids.

The apparatus of the present invention may also comprise a means ofgenerating an electric field between the photoresist film-removersupplier and the substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically shows a cross-sectional view of an apparatus (A1)for removing the photoresist film according to the present invention asan embodiment 1.

FIG. 2 shows a graph illustrating a maximum rate of removing thephotoresist film versus a coating thickness of the photoresistfilm-remover on the surface of the substrate to be processed.

FIG. 3 shows a graph illustrating a maximum rate of removing thephotoresist film and a degree of an in-plane uniformity on the surfaceof the substrate versus a distance (δ) between the photoresist film andthe photoresist film-remover supplier in the method of the presentinvention.

FIG. 4 schematically shows a cross-sectional view of an apparatus (A2)for removing the photoresist film as an embodiment 2 of the presentinvention, wherein the apparatus may generate an electric field betweenthe photoresist film and the photoresist film-remover supplier.

FIG. 5 schematically shows a cross-sectional view illustrating anapparatus (A3) for removing the photoresist film as an embodiment 3 ofthe present invention.

FIG. 6 schematically shows a cross-sectional view illustrating anapparatus (A4) for removing the photoresist film according to anembodiment 4 of the present invention, wherein the apparatus can supplythe mixture of the ozonized gas and the photoresist film-remover.

FIG. 7 schematically shows a cross-sectional view illustrating anotherapparatus (A5) for removing the photoresist film according to theembodiment 4 of the present invention, wherein the apparatus can supplythe mixture of the ozonized gas and the photoresist film-remover.

FIG. 8 schematically shows a cross-sectional view illustrating anapparatus (A6) for removing the photoresist film of the presentinvention as the embodiment 5.

FIG. 9 schematically shows a cross-sectional view illustrating a washingapparatus used in a method described in Japanese Patent KokaiPublication No. Sho 57 (1982)-180132, for removing the photoresist filmapplied on the substrate or the insulating layer by bubbling theozonized gas in hot sulfuric acid.

PREFERRED EMBODIMENTS OF THE INVENTION

A method of the present invention and an apparatus used in the methodwill be described in detail below by way of preferred embodiments. Itshould be noted, however, that the present invention is not limited tothese embodiments, and various changes and modifications that areapparent for those skilled in the art are within the scope of thepresent invention.

Embodiment 1

FIG. 1 shows an aspect of the apparatus used for the method of thepresent invention. FIG. 1 illustrates one example of an apparatus forprocessing a substrate, in which a substrate having photoresist filmformed on the surface of the substrate is charged one by one to process(generally called a “single wafer processing apparatus” in the art).

In the present application, the photoresist film to be removed mayinclude either a film formed from a photoresist material containing anorganic polymer compound, which the photoresist material is used in anyprocesses of manufacturing semiconductor devices, a film decomposed byheating, a film of which the surface is modified by heating or heavydoping, or a film having a surface on which an inorganic substance isdeposited in an etching process.

For a substrate having the photoresist film on the surface thereof,there is no particular limitation as long as the substrate is of thetype commonly used in the production of semiconductor devices and, forexample, silicon wafer, glass substrate for liquid crystal displaydevice, glass epoxy sheet for packaging electronic circuits and the likeare included.

The substrate of which the surface has the photoresist film may includesilicon wafer, a glass substrate for a liquid crystal display device, aglass-reinforced epoxy substrate used for producing a printed-circuit,and the like, but is not particularly limited thereto as long as it maybe any one commonly used in the manufacture of semiconductor devices.

An apparatus (A1) of the present invention shown in FIG. 1 has a stage40 that carries the substrate 8 fixed thereon and can be trochoid at thecenter of mass thereof, and a gas/liquid supplier 30 disposed as opposedto the stage 40, in a closed space covered with a reaction vessel 6.

In the stage 40, there has a heating means 41 capable of heating thesubstrate 8 laid on the stage 40. The rotation and the heating of thestage 40 are controlled by a control unit 42 disposed below the reactionvessel 6.

The gas/liquid supplier 30 is provided with an ozonized gas feed tube 31at the center of the supplier 30, and a photoresist film-removerreservoir 32 around the ozonized gas feed tube 31, as well as aphotoresist film-remover injection outlet 33 provided below thereservoir 32.

An oxygen-containing gas as a stock gas is supplied through a gas feedtube 111, and then at least 5 mole %, preferably from 5 to 100 mole % oftotal amount of the gas containing oxygen gas is converted to ozone byan ozone generator 1 to obtain the ozonized gas.

More amount of ozone is contained in the ozonized gas, higher rate ofremoving the photoresist film is obtained, but the amount of ozonecontained in the ozonized gas may be varied depending on the size of thesubstrate to be processed and the type of the photoresist used in theprocess. An amount of the oxygen-containing gas fed to the ozonegenerator 1 may be varied depending on the required amount of theozonized gas to be supplied and on an actual amount of the ozonized gassubsequently supplied to the substrate.

In the apparatus (A1) shown in FIG. 1, the ozonized gas is controlled toa predetermined pressure before the supplement thereof through the feedtubes 112 and 31 to the substrate 8.

The photoresist film-remover that can be used in the present inventionmay be selected from a group consisting of pure water; an aqueous acidsolution such as sulfuric acid, hydrochloric acid, nitric acid, aceticacid and hydrogen peroxide; an aqueous alkaline solution such asammonium hydroxide; an organic solvent including ketones such as acetoneand alcohol such as isopropanol; and a mixture thereof, having lowreactivity with ozone. Although the use of pure water is most preferablein view of the disposal of waste liquid or gas and the like, it isdesired to use a solvent other than pure water or a mixture thereof whenit is intended to increase a rate to remove the photoresist film, or toremove a film that has been modified by heavy ion doping or contaminantsdeposited on the substrate.

The photoresist film-remover is fed through the feed tube 114 into thephotoresist film-remover reservoir 32 in the reaction vessel 6, and isejected from the outlet 33 distributed therebelow toward the substrate 8when required.

The process of removing the photoresist film using the apparatus (A1)shown in FIG. 1 will be described below.

First, the substrate is fixed on a stage 40. Then the ozonized gas andthe photoresist film-remover are supplied through the feed tube 31 andthe injection hole 33 to the substrate 8, respectively. The ozonized gasand the remover supplied through the feed tube 31 is spattered from thecenter to the periphery of the substrate 8, and contact with the wholeof the photoresist film.

While the photoresist film on the substrate surface is oxidized anddecomposed by contacting with the ozonized gas, and reduces themolecular weight of an organic component contained in the photoresistfilm, a coating of the photoresist film-remover is formed on thephotoresist film. The photoresist film having the reduced molecularweight may be dissolved in the coating of the photoresist film-remover,washed off by another supplement of the photoresist film-remover, andthen removed from the surface of the substrate.

In the apparatus (A1) according to the present invention shown in FIG. 1the ozonized gas is supplied at a constant high pressure from a positioncorresponding to the center of the substrate.

The present inventors have found that the pressure of the ozonized gassupplied to the apparatus has functionality to the rate to remove thephotoresist film, and that when the pressure increases, the rate can beimproved substantially in proportion to the pressure. Accordingly, inthe present invention, the ozonized gas is supplied at a constant highpressure between preferably from 1 atm (101, 325 Pa) and 5 atms (506,625 Pa), in view of the reliability and the safety of the apparatus usedin the process, in the present invention.

Additionally, in the present invention, the ozonized gas is preferablysupplied continuously. By continuously supplying the ozonized gas, ozonecan be maintained to uniformly supply to the entire surface of thesubstrate even when ozone contained in the ozonized gas contacts withthe photoresist film and is consumed by the oxidation and decomposition,and at the result, the uniform removal of the photoresist film can beachieved.

Although ozone contained in the ozonized gas is preferably consumed onlyin the reaction of removing the photoresist film, ozone may be consumedby reacting with materials other than the photoresist film (for example,inner wall of the reaction vessel or a part of the apparatus, or thelike) because of the high reactivity of ozone. In order to avoid suchwaste of ozone, the reaction vessel and the part of the apparatus may bepreferably made of stainless steel or Teflon®-coated stainless steel,Teflon® resin, ceramics or Teflon®-coated ceramics, or a mixturethereof.

At the same time of the supplement of the ozonized gas, the photoresistfilm-remover is supplied from the plural photoresist film-removeroutlets 33 provided in the gas/liquid supplier 30.

In order to achieve effective removal of the photoresist film, at leastten outlets 33 may be preferably distributed corresponding to the wholesurface of the substrate 8, each of which a diameter is about 1 mm orless.

As the photoresist film-remover is supplied as described above, it maybe observed that a thick coating of the solution is formed on thesurface of the photoresist film. FIG. 2 illustrates the relation of thecoating thickness of the remover (mm) to the maximum rate to remove thephotoresist film. The coating thickness is determined by visualobservation. FIG. 2 shows that the rate to remove the photoresist filmcan be sufficiently high when the coating thickness is 1 mm or less. Itis due to that less thickness of the coating formed on the photoresistfilm is, easier ozone penetrates to the coating.

However, since the coating thickness of 1 mm or less is difficult toform by continuously supplying the remover, the photoresist film-removeris preferably supplied intermittently (most preferably every 1 to 360seconds) according to the present invention.

The present inventors have also found that in the apparatus describedabove, the rate to remove the photoresist film is significantly affectedby the distance between the gas/liquid supplier 30 including theozonized gas feed tube 31 and the surface of the substrate 8 (denoted asδ in FIG. 1).

FIG. 3 illustrates variations of both maximum rate to remove thephotoresist film and a degree of the in-plane uniformity of the rate onthe substrate as a function of the distance (mm). FIG. 3 shows that lessthe distance is, higher the maximum rate is, and that more the distanceis, higher the degree of the in-plane uniformity. This results withreference to FIG. 1 is considered as follows: Since less the distancebetween the gas/liquid supplier 30 and the surface of the substrate 8is, faster the flow rate of the ozonized gas through the clearancebetween them is, and thereby the apparent amount of ozone supplied tothe surface of the substrate may increase, the rate of the oxidation andthe decomposition of the photoresist film may be also improved. However,when the distance is too narrow, there may occur a position where theflow of the ozonized gas on the surface of the substrate becomesnon-uniform.

Based on the above discussion, the distance (δ) between the gas/liquidsupplier 30 and the surface of the substrate 8 is preferably set in arange from about 1 to 5 mm.

In order to carry out the removal of the photoresist film moreefficiently using the method of the present invention, the substrate maybe heated. Heating of the substrate 8 is conducted using the heatingmeans 41 provided in the stage 40 (FIG. 1). The temperature of theheating means 41 may be controlled by a control unit 42 laid below thereaction vessel 6.

Although the oxidizing and decomposition reaction of the photoresistfilm with ozone is accelerated as the substrate is heated to a highertemperature, the substrate may be damaged when the temperature is toohigh. Therefore, the temperature of substrate heated may be varieddepending on the type of substrate used. For example, when using siliconwafer as the substrate, the temperature is preferably about 300° C. orless, when using glass substrate, it is preferably about 100° C. orlower.

When the substrate is heated as described above, the decomposition ofozone is also accelerated and the release of oxygen atoms having highreactivity of oxidization is increased, and thereby, the rate to removethe photoresist film by the decomposition may be also improved. At thesame time, however, an increased temperature in the vicinity of thesubstrate may also cause the temperature of the ozonized gas feed tube31 to rise. Thus ozone may be thermally decomposed in the feed tube sothat the active oxygen atoms is sometimes impossible to reach thesurface of the substrate.

Therefore, in the apparatus (A1, FIG. 1) of the present invention, sincea temperature of the photoresist film-remover is lowered using a cooler115 before its introduction to the reservoir 32, the ozonized gas feedtube 31 adjacent to the reservoir 32 may be cooled, and thereby thethermal decomposition of ozone other than in the vicinity of the surfaceof the substrate 8 can be prevented.

According to the present invention, in order to make it easier to supplythe ozonized gas and the photoresist film-remover to the entire surfaceof the substrate, the substrate may be trochoid at the center of massthereof by rotating the stage 40 shown in FIG. 1. Rotation of the stage40 can be control-led with the control unit 42 to a desired speed.

In the apparatus (A1) of the present invention, an excess of thesupplied photoresist film-remover 5 may be collected in the reactionvessel 6 and then reused. The collected remover may be passed through afilter or the like (not shown) to remove a residue of the photoresistfilm therefrom, and then sent through the cooler 115, the pump 4 and thefeed tube 114 to reuse as the photoresist film-remover 5.

In the apparatus of the present invention, after an excess of thesupplied ozonized gas is sent to a waste ozone processing device 13through an ozonized gas discharge tube 112′, the remaining ozone isconverted to oxygen to release to the atmosphere, and therefore,atmospheric pollution by ozone can be prevented (FIG. 1).

According to the present invention, since the photoresist film isremoved in the sealed container, harmful gas is not released to theatmosphere without requiring a large-scale ventilation facility.Material cost can also be reduced because the photoresist film-removerused in the process is circulated after the operation.

Embodiment 2

It has been described hereinbefore that according to the presentinvention, the rate to remove the photoresist film can be significantlyincreased by decreasing the thickness of the coating of the photoresistfilm-remover formed on the photoresist film to be treated. However,decreasing the thickness of the coating may be accomplished not only byintermittently supplying the remover as described in the embodiment 1,but by applying an electric field between the gas/liquid supplier 30 andthe substrate 8 as shown in FIG. 4.

FIG. 4 shows an example of an apparatus (A2) including a means forgenerating an electric field between the supplier 30 and the substrate 8laid on the stage 40. In the apparatus (A2), the gas/liquid supplier 30can be applied at several kilovolts or higher, and the stage 40 isgrounded. The photoresist film-remover is supplied either continuouslyor intermittently, preferably intermittently. Applying the high voltageto the gas/liquid supplier 30 may be preferably performed when thephotoresist film-remover is supplied from the outlets 33.

As the electric field is generated between the supplier 30 and thesubstrate 8 on supplying the photoresist film-remover, the removerejected from the outlets 33 is spattered in the form of tiny droplets bythe action of the electric field. The droplets of the remover may resultin a very thin coating when it is deposited on the photoresist film onthe surface of the substrate. As the remover is converted to the verythin coating, the oxidization and decomposition reaction with ozone maybe accelerated, and at the result, the rate to remove the photoresistfilm may be increased.

As used herein, the means for generating the electric field shown inFIG. 4 is intended to be a mere example so that the present invention isnot limited thereto. The apparatus (A2) shown in FIG. 4 may be the sameas the apparatus (A1) described in the above embodiment 1, with theexception of the means described above, elements and functionsspecifically described above.

Embodiment 3

For the apparatus used for the method of the present invention, in theembodiments 1 and 2, the ozonized gas is supplied from the ozonized gasfeed tube 31 corresponding to the center of the substrate, and thephotoresist film-remover is supplied from the photoresist film-removerinjection outlet 33 located on the periphery of the feed tube 31 (A1 andA2 shown in FIG. 1 and FIG. 2). Herein, each positions of supplying theozonized gas and the photoresist film-remover may be interchanged ifrequired.

For example, as shown in an apparatus (A3) of FIG. 5, the photoresistfilm-remover may be supplied from the feed tube 31 corresponding to thecenter of the substrate and the ozonized gas may be supplied from theoutlets 33 located on the periphery of the feed tube 31.

In this case, preferably, the ozonized gas is continuously supplied andthe photoresist film-remover is intermittently supplied, but theseconditions for preparing the ozonized gas and the type of thephotoresist film-remover used in the process may be the same as thosedescribed in the embodiment 1.

The apparatus used in this embodiment 3 may be the same as that of theembodiment 1, with the exception of the means and conditions used forsupplying as described above.

Embodiment 4

According to the present invention, the ozonized gas and the photoresistfilm-remover may be supplied to the reaction vessel 6 either separatelyor as a mixture thereof. The embodiments 1 to 3 have described for themethods and apparatuses used to separately supply the ozonized gas andthe photoresist film-remover. In this embodiment 4, the method andapparatus will be illustrated below, including mixing the ozonized gasand the photoresist film-remover to supply a mixture thereof to thereaction vessel 6 (FIG. 6 and FIG. 7), in order to make it easier tosupply the ozonized gas and the photoresist film-remover to the entiresurface of the substrate.

In the apparatuses (A4 and A5) shown in FIG. 6 and FIG. 7, while theozonized gas generated in the ozone generator 1 is sent through the feedtube 111 to the ejector 2 and, the photoresist film-remover is suppliedthrough the feed tube 114 to the ejector 2. After mixing the ozonizedgas and the photoresist film-remover in the ejector 2, the mixture issupplied through the feed tube 112 to the supplier 30′ (FIG. 6) or 31′(FIG. 7). Thus, the apparatus (A4) shown in FIG. 6 equips a reservoir32′ and a outlet 33′ in the supplier 30′, similar to those of theapparatus (A1) of the embodiment 1, so that the mixture may be ejectedfrom the outlets 33′ to the substrate. Alternatively, in the apparatus(A5) shown in FIG. 7, the mixture can be supplied directly from the feedtube 31′ distributed at a position corresponding to the center of thesubstrate.

In this embodiment 4, concentration of the ozonized gas incorporatedinto the photoresist film-remover, particularly the effectiveconcentration of the ozonized gas incorporated, may be varied dependingon an amount of ozone contained in the ozonized gas and the type of theremover used in the process. For example, when pure water is used as theremover, the amount of ozone may be, preferably in the state ofsaturation, within a range from about 10 to 200 ppm at 20° C.

Further, in the method and apparatus of this embodiment 4, it ispreferable that the ozonized gas is continuously supplied and thephotoresist film-remover is intermittently supplied, in order toincrease the rate to remove the photoresist film. That is, in theapparatuses (A4 and A5) according to the present invention, for example,the mixture and the photoresist film-remover containing no ozonized gascan be supplied alternately onto the surface of the substrate.

In either of the apparatuses shown in FIGS. 6 and 7, the substrate canbe trochoid at the center of mass thereof in the same way as describedin the embodiment 1, in order to make it easier for the mixture and theremover to diffuse to the entire surface of the substrate.

The apparatus used in this embodiment 4 may be the same as that of theembodiment 1, with the exception of the devices, functions andconditions specifically described.

Embodiment 5

In an apparatus (A6) of this embodiment 5, that is a further improvedversion of the apparatus of the embodiments 1 to 3 according to thepresent invention, providing that the ozonized gas from the ozonegenerator 1 can be ensured to supply in a sufficient amount to process,the end opening of the ozonized gas feed tube 31 may be expanded towardthe substrate 8 in a radially widened shape like a bell flare of atrumpet as shown in FIG. 8.

When the radius (or a length of the longitudinal side) of the substrateis r, the end opening of the ozonized gas feed tube 31 may be radiallyexpanded toward the substrate gradually with a gradient of approximately1/r. The widened shape may have a curved portion such as in the bellflare of a trumpet.

Such shape of the end opening of the ozonized gas feed tube 31 makes itpossible to supply the ozonized gas more uniformly and more efficientlyto the entire substrate.

In this embodiment 5, an injection outlet (not shown in FIG. 8) forejecting the photoresist film-remover to the substrate 8 may be furtherprovided along the end opening of the ozonized gas feed tube 31.

Effects of the Invention

According to the method of the present invention, since the photoresistfilm is removed in the sealed system and the photoresist film-removercan be circulated to reuse, costs of both ventilation facility and thestarting material can be significantly reduced. Because the apparatusaccording to the present invention has an exhaust system, air pollutiondue to the discharge of an excess of the supplied ozone can beprevented.

According to the present invention, the rate to remove the photoresistfilm can be increased several times over the prior art because of thefollowing capabilities:

-   -   (1) to supply the ozonized gas and the photoresist film-remover        to the photoresist film evenly and either continuously or        intermittently;    -   (2) to use ozonized gas, which contains ozone used to oxidizing        and decomposing the photoresist film in a larger amount than the        conventional way;    -   (3) to set the distance between the surface of the photoresist        film applied on the surface of the substrate and the photoresist        film-remover supplier disposed as opposed to the photoresist        film former in most effective range (particularly, between 1 and        5 mm); and    -   (4) to supply the ozonized gas at a high pressure from 1 atm        (101, 325 Pa) and 5 atms (506, 625 Pa).

According to the present invention, the ozonized gas and the photoresistfilm-remover may be supplied either separately or in a form of amixture. In either case, since the ozonized gas can be continuouslysupplied and the photoresist film-remover can be intermittentlysupplied, the rate to remove the photoresist film may be furtherincreased.

Since the apparatus that is the second aspect of the present inventionis made of a material which does not react with ozone, the ozonized gascan be effectively used only in removing the photoresist film.

In the apparatus of the present invention, the ozonized gas and thephotoresist film-remover can be continuously or intermittently suppliedfrom the same nozzle or different outlets provided in the photoresistfilm-remover supplier onto the substrate surface to use as thephotoresist film removable mixture. The ozonized gas contains in anamount of at least 5 mole %, preferably from 5 to 100 mole % of ozone.

In the apparatus of the present invention, the rate to remove thephotoresist film can be increased by incorporating the ozonized gas intothe photoresist film-remover to supply a mixture thereof to thephotoresist film.

Since the apparatus of the present invention includes a means forheating the stage and/or a means for cooling the photoresistfilm-remover, the temperature of the photoresist film-remover and thetemperature at a position 5 mm or more away from the substrate can beset lower than the temperature on the surface of the substrate, andthereby the rate can be further increased.

Since the apparatus of the present invention is capable of supplying theozonized gas at a high pressure in a range from 1 atm (101, 325 Pa) and5 atms (506, 625 Pa), the sufficient amount of ozone can be caused toact on the photoresist film. The photoresist film-remover used in thepresent invention may be selected from any of those commonly used.

In addition, according to the present invention, a means for generatingthe electric field between the photoresist film-remover supplier and thesubstrate to convert the photoresist film-remover to a microparticle canbe installed in the apparatus of the invention, and thereby, the rate ofthe oxidization and decomposition of ozone may be accelerated. As theresult, it can provide a higher rate to remove the photoresist film.

1. An apparatus for removing a photoresist film from a surface of asubstrate in a sealed system, the apparatus comprising: a reactingchamber, an ozonizer producing an ozonized supplied to the reactingchamber, an exhaust system exhausting the ozonized gas from the reactingchamber, a stage for mounting of a substrate having a surface coveredwith a photoresist film, a photoresist film-remover supplier disposedopposite the stage, the stage and the photoresist film-remover supplierbeing disposed in the reacting chamber, means for supplying aphotoresist film-remover and the ozonized gas to the surface of thesubstrate through apertures in the photoresist film-remover supplier,and means for generating an electric field between the photoresistfilm-remover supplier and the substrate.
 2. The apparatus for removing aphotoresist film according to claim 1, wherein the reacting chamber isselected from the group consisting of stainless steel, polytetrafluoroethylene coated stainless steel, polytetrafluoroethylene resin,ceramics, polytetrafluoroethylene-coated ceramics, and combinationsthereof.
 3. The apparatus for removing a photoresist film according toclaim 1, further comprising means for heating the stage.
 4. Theapparatus for removing a photoresist film according to claim 1, whereina surface of the photoresist film and the photoresist film-removersupplier are separated by a distance within a range of 1 to 5 mm.
 5. Theapparatus for removing a photoresist film according to claim 1, furthercomprising means for cooling the photoresist film-remover.
 6. Anapparatus for removing a photoresist film from a surface of a substratein a sealed system, the apparatus comprising: a reacting chamber, anozonizer producing an ozonized gas supplied to the reacting chamber, anexhaust system exhausting the ozonized gas from the reacting chamber, astage for mounting of a substrate having a surface covered with aphotoresist film, a photoresist film-remover supplier disposed oppositethe stage, the stage and the photoresist film-remover supplier beingdisposed in the reacting chamber, and means for supplying a photoresistfilm-remover and the ozonized gas to the surface of the substratethrough apertures in the photoresist film-remover supplier, thephotoresist film-remover supplier including a feed tube centrallylocated in the means for supplying and having a single aperturedischarging toward the substrate only one of the ozonized gas and thephotoresist film-remover, and a reservoir including a plurality ofapertures discharging toward the substrate the other of the ozonized gasand the photoresist film-remover, wherein the reservoir surrounds and issealed with respect to the feed tube.
 7. The apparatus for removing aphotoresist film according to claim 6, wherein the reacting chamber isselected from the group consisting of stainless steel,polytetrafluoroethylene coated stainless steel, polytetrafluoroethyleneresin, ceramics, polytetrafluoroethylene-coated ceramics, andcombinations thereof.
 8. The apparatus for removing a photoresist filmaccording to claim 6, further comprising means for heating the stage. 9.The apparatus for removing a photoresist film according to claim 6,further comprising means for cooling the photoresist film-remover. 10.The apparatus for removing a photoresist film according to claim 6,wherein a surface of the photoresist film and the photoresistfilm-remover supplier are separated by a distance within a range of 1 to5 mm.
 11. An apparatus for removing a photoresist film from a surface ofa substrate in a sealed system, the apparatus comprising: a reactingchamber, an ozonizer producing an ozonized gas supplied to the reactingchamber, an exhaust system exhausting the ozonized gas from the reactingchamber, a stage for mounting of a substrate having a surface coveredwith a photoresist film, a photoresist film-remover supplier disposedopposite the stage, the stage and the photoresist film-remover supplierbeing disposed in the reacting chamber, a container for holding a liquidphotoresist film-remover, and an ejector for mixing the ozonized gas anda photoresist film remover to produce a photoresist film-removal mixtureincluding the photoresist film-remover and the ozonized gas, thecontainer and the ejector being disposed outside the reacting chamber,and means for supplying the photoresist film-removal mixture to thesurface of the substrate through apertures in the photoresistfilm-remover supplier, wherein the photoresist film-remover supplierincludes a peripheral reservoir including a plurality of apertures,surrounding a central portion free of apertures, discharging toward thesubstrate the photoresist film-removal mixture.
 12. The apparatus forremoving a photoresist film according to claim 11, wherein the reactingchamber is selected from the group consisting of stainless steel,polytetrafluoroethylene coated stainless steel, polytetrafluoroethyleneresin, ceramics, polytetrafluoroethylene-coated ceramics, andcombinations thereof.
 13. The apparatus for removing a photoresist filmaccording to claim 11, further comprising means for heating the stage.14. The apparatus for removing a photoresist film according to claim 11,further comprising means for cooling the photoresist film-remover. 15.The apparatus for removing a photoresist film according to claim 11,wherein a surface of the photoresist film and the photoresistfilm-remover supplier are separated by a distance within a range of 1 to5 mm.